Plants of the Amazon Rainforest Hence, a traveller should be a botanist, for in all views plants form the chief embellishment. C. Darwin, HMS Beagle
The Amazon Rainforest biome 2,100,000 sq mi an estimated 390 billion individual trees divided into 16,000 species
The Amazon is one of the true Tropical Rainforests on earth
The climate maintains a dense and diverse plant cover red and purple colors: rainforest cover green: (savannas) shades of green
Geologic forces during the Cenozoic (65.5MY to present) created the forest Andean uplift created the environmental conditions that promoted plant and animal diversity
The forest has been in existence for at least 55 million years
The Amazon Rainforest contains c80,000 species of flowering plants out of 422,000 world-wide
and roughly 30 Million species of Insects Titanus giganteus 700 species of beetle discovered on just one tree.
The flora is extremely diverse, with up to 300 species/acre Socratea exorrhiza Bertholletia excelsa Brazil Nut
But very few individuals per species This is in contrast to what is found in Northern forests
Zones, or layers of the tropical rainforest
Top layer: Emergent trees Ceiba pentandra Kapoc
The tallest trees are the emergents, towering as much as 200 feet above the forest floor with trunks that measure up to 16 feet around. Wimba: Ceiba samauma 55m Brazilian mahogany Swietenia macrophylla, 70m Brazil nut, 50m Lupuna (Kapoc): Ceiba pentandra 55m
Many emergents have Buttress Roots Ceiba pentandra
Closed layer: the Canopy
The canopy contains most of the life of the forest Epiphytes insects (25% of all species) lianas and vines canopy trees
Epiphytes: Plants that grow on plants
Orchids
Bromeilads
Ferns Staghorn fern Bird s nest fern
Lianas (woody vines) Bauhinia (pea family)
Understory
Plants need to be shade tolerant as only 5% of the available sunlight reaches this layer
Palms are well represented 34 genera (24% endemic), 189 species Desmoncus mitis The Amazon contains about 50% of the New World species
Aroids Caladium bicolor Alocasia amazonica
Ferns Hymenophyllum sp Filmy fern Microgramma lycopodioides Adiantum macrophyllum
The forest floor Plants adapted to low light fungi bacteria
The soil depth is often <2
Roots for an intertwined mat on top of the soil
Saprophytes: Fungi and Bacteria Termite bacteria
Roots (probably) always are associated with fungi Mycorrhiza
Nutrients are recycled almost immediately and absorbed by the biomass above
Due to this symbiotic relationship, nutrients are almost 100% recycled Nutrients (C and N) Biomass (plants & animals) = 50% Forest floor and the first 50cm of soil = 40% Microbial and Fungal activity in Rivers and the Forest floor convert biomass back into CO2 45% from soil 55% from rivers 5% of the Carbon reaches the ocean.
Adaptations of plants to the Rainforest
Roots Plants modify their three organs Stem Leaves
Roots Plants of the rainforest have adapted to their epiphytic habit prop palms buttress Ceiba clasping Philodendron aerial/contractile figs absorptive orchids
Prop Roots
Buttress Roots
Clasping Roots Phyllodendron
Aerial Roots, strangler figs
Absorptive Roots Orchids
Adaptations of leaves
Leaf shape Entire margin, thick and tough, often waxy Young leaves reflexed and red pigmented
Large leaves capture light Victoria amazonica Manicaria saccifera Leaves up to 30 ft long Alocasia
Leaves form a tank The leaves overlap to form a tank that catches water and detritus. Hairs at the base of the leaves absorb nutrients. Also, this genus can transform it s photosynthetic mechanism to a more drought-tolerant pathway (C3 -> CAM) during water stress.
Leaf Drip-Tip
Modifications of the Stem
Prickly Stems Ceiba pentandra kapoc Desmoncus orthacanthos Palm
Climbing stems Ribbon vine of Bauhinia guianensis
Stolons for vegetative reproduction Salvinia
Fruit dispersal
Hard Palm fruits are dispersed by large animals Attalea palm Agouti New World monkeys Astrocaryum palm
Smaller fruits are dispersed by smaller animals Three-toed sloth Fig tree
Really large fruits may have evolved when South America had Megafauna Glyptodon Megatherum Couroupita guianensis Cannonball tree Theobroma cacao cacao Cuvieronius
Some fruits have been especially taken care of by humans! Next Time!